Means and method for filling molds with molten metal



May 13, 1930. A. KADOW.

MEANS AND METHOD FOR FILLING MOLDS WITH MOLTEN METAL Filed March 15, 1926 2 sheets-sheet 1 Auyuat Ka do? May 13, 1930. A. KADOW Filed March 15, 1926 'zshe ets-Sheet' 2 1 1 j fluy uat Kadow @AA /u/ 3 M Patented May 13, 1930 um'rso STATES PATENT orncs AUGUST KADOW, OF TOLEDO, OHIO, ASSIGNOR, BY DIRECT AND MESNE ASSIGNMENTS, TO THE VACUUM CASTING COMPANY, OF TOLEDO, OHIO, A CORPORATION OF OHIO MEANS AND METHOD FOR FILLING MOLDS WITH MOLTEN METAL M invention relates to means and methodof ing a mold with molten metal, and has for its object to completely fill a mold with molten metal under pressure while avoiding dan er ofblow Holes.

fien metal is forced into a mold under considerable pressure the entering jets of metal frequently set up eddy-currents and cause the metal to solidify around air pockets, leaving blow holes in the casting. When metal is forced in under pressure higher than atmospheric, it is evident that such eddy-currents readily trap air in the casting. When the mold cavity is evacuated and metal is forced in by atmospheric pressure, there is comparatively little air in the mold cavity to be entrapped, but in spite of this fact it is found that the metal is apt to set around cavities where it spurts into the mold.

When the metal is introduced into the mold under lower pressure, so that no jets are formed, there is danger of the metal setting before it flows into all of the remote portions of the mold cavity. This is particularly true when the cast article has projections'of'com siderable length in proportion to their diameter.

In order to avoid both of these difliculties I reduce the initial speed of flow into the mold cavity, so as to avoid spurting the metal into the mold in jets, and at the same time I providefor the final filling of the mold under comparatively high pressure.

This object may be accomplished in several different ways. It is possible to fill the mold by means ofan initial low vacuum and final high vacuum, or by an initial low pressure upon the entering metal with increasing pressure as the mold filled; but the mold is filled so quickly in ordinary operation that controlling the entrance of the metal by controlling the degree of vacuum within the mold cavity or by controlling the pressure upon the metal presents great difiiculties, and therefore I prefer to accomplish my object by a modification of the inlet opening or openings along the lines which will now be described. In the accompanying drawings, forming a art of this specification, Figure 1 is an ele- 50 vation of the inside of one-half of a mold Application filed March 15, 1926. Serial No. 94,716,

embodying one form of my invention; Figs. 2 and3 are enlarged sections alon lines 2-2 and 33 respectively on Fi 1 ig. 4.- is a partial elevation similar to ig. 1 showing a modified form of mold inlet; Fi 5 is a section on the line 5-5 of Fig. 4; ig. 6 is an enlargement of a portion of Fig. 4;, and Figs.

7 and 8 are sections on the lines 7+7 and 8-8, respectively, Fig. 6.

In the construction shown in Fig. 1 there is shown a mold-half 10, which is adapted to cooperate with a similar mold-half in a well known manner to form a mold cavity.

As the two halves are, or may be, constructed the same, itis necessary to describe but one of the halves. I

The mold is constructed with a cavity 11 in which the desired casting is formed. Grooves 12'-12 in the mold face lead to a suitable outlet 13 connecting to any suitable means for exhausting the air from the mold. The partitions 14 between the passages 12 sage of molten metal.

Inthe form of mold shown in Fig. 1 there 1s an lnlet opening 15 leading into a reservoir 16, from which a plurality of openings 17 lead into the mold cavity 11. As will be readily seen from a comparison of Figs. 2 p

and mold cavity 11 may be left flush with I the rest of the mold wall, and still air will pass from cavity 11 to passages 12 more and 3, the total cross-section of passages 17].

is considerably in excess of the cross-sectiom of passage 15; also the mold is not cut away at 18 directly opposite the entrance 15, so that this portion 18 forms a baflie to intercept the stream of metal entering-through,

inlet 15 and prevent its spurting directly into the mold.

It will be readily understood that in operation, when the lower end of the mold is dipped into a bath of molten metal and mold cavity 11 is evacuated, atmospheric pressure forces the molten metal through inlet and against baffle 18, whence it spreads out in greater than the cross-section of passage 15,

the flow of metal throughpassages 17 into the mold will be at considerably less velocity than the flow of metalthrough passage 15, and in this way the tendency of the metal to enter the moldin jets which form blow holes is avoided. At the same timeit will be clear that, if the metal should become somewhat stiff before the upper portion 19 of mold cavity 11 becomes completely filled, the

entire differential pressure between atmo'spheric pressure and the degree of vacuum contained in the mold would be exerted upon the metal to complete the filling of this por tion of the mold.

While this structure is shown and described as applied to a mold intended to be filled by the suction method, it will be clear that the same result in controlling the flow of metal into the mold would be achieved if metal were forced through inlet 15 under pressure other than or pheric.

,In the form of inlet shown in Fig. 4, a similar efiectupon the flow of metal into the mold is achieved by a somewhat different structure.

In this formthere is shown a mold similar to that shown in Fig. 1, and having like parts indicated by the same reference numbers with the addition of the letter a, the'difierence between the two molds bein in the construction of the inlet openings. 11 the form shown in Fig. 4 there are a plurality of inlet openings 20. Interposed between each pair of inlets 20'there is a partition 21. The upper ends of passages 20 are made considerably wider than the lower ends' and the intervening partitions 21 are preferably of stream line formation, their lower ends being at the widest pointin the formation.

Interposed in the center of each passage 20, immediately above the inlet opening, is a baflle or stream-divided 22. These baffles 22 are also preferably of stream line formation,

' but in this case the entire formation is completed. In this way the metal entering through a passage 20 is divided into two 'channels' each of which gradually increases The form of inlet shown in Fig. 4 is adgreater than atmosthe inlet shown in Fig. 4 requires greater care and exactness in formation, and, increases the first cost of the mold.

It will be evident that the form of gate shown in Fig. 4 is equally well adapted for filling 'a suction mold or filling a mold where the metal is introduced under pressure other than atmospheric.

In both instances the metal has been shown entering the mold cavity from the bottom. Some of the advantages of my invention could be realized where the metal is introduced into the upper portion of the mold through gravity or otherwise, but where so introduced there is a ays a tendency for the metal to form into streams which flow through the mold cavity to itsbottom and result in a certain amount of spraying and splashing of the metal with resultant danger of blow holes. Therefore, I prefer to-introduce the metal at the bottom or at the substantially lowest point in the mold cavity.

therefore,

When so introduced and properly controlled the metal flows into the mold gradually and no jets are created within the mold cavit I have shown two forms "of mold inlhts, both of which are well adapted for use with suction molds and for use with narrow inlet slots, .such as described and claimed in my co-pending application Serial No. 94,712 for Process and apparatus for casting liquid molten metal, now Patent N 0. 1,606,236.

It will be readily understood that other forms of inlet openings may be devised, both where narrow inlet slots are used and where inlet openings of other shapes are formed, without departing from the spirit of my invention.

It will be clear also that, when using a mold with an inlet similar to that shown in Fig. 1 and wherein a reservoir like reservoir 16 is provided, the inlets 17 may be made narrow enoughto prevent the escape of metal y stantially circular, if desired, and large enough so that the molten metal remaining in reservoir 16 will flow back out through lifted from the inlet 15 when the mold is bath.

The effect of inlets of the form shown in Figs. 1 and 4 is to hafile the entering jets of molten metal and to reduce the pressure and the velocity with which they enter the mold cavity until the cavity is nearly filled, but when any resistance is offered to the further entrance of moltenmetal, the full pressure of the metal at the initial or outside opening is available to overcome this resistance and completely fill the mold. Therefore, these inlets'have the efi'ect of automatically governing the pressure so that the main part of the the benefits of both low pressure and high,

having an inlet opening in its bottom, the

mold cavity is filled at low pressure, while the final filling is .done at high pressure.

It will be seen therefore, that the velocity of the metal first entering the mold is sufficiently reduced to avoid blow holes caused by spurting jets, and at the same time the maximum pressure available for completely filling comparatively long and narrow mold cavities, or projections from the main cavity, is not reduced. By the structure of the inlet,

filled and increasing, during the filling process, the difierential between the pressure of gases on the surface of the metal rising in the cavity and the fluid pressure forcing metal into the cavity.

2. The process of casting metal, which consists in introducing molten metal into a mold cavity at the lower portion thereof, governing the velocity of the metal first entering the cavity so that jets will not be formed, and completing the filling of the cavity under comparatively high pressure.

3. The process of casting metal, which consists in passing metal upward from a molten bath thereof into the lower portion of a mold cavity in a stream increasing in cross-section as it approaches the mold cavity.

4. The process of casting metal, which comprises forcing the metal upward from a molten "bath thereof under comparatively high pressure, intercepting the metal passing from the bath and changing its direction while increasing the cross-section of the flowing metal, and introducing the metal into the bottom of the mold cavity in such increased cross-section.

5. In apparatus for casting metal, a mold cross-section of said opening being materially greater where it joins the-mo1d cavity than at the exterior surface of the mold.

6. In apparatus for casting metal, a mold having an inlet opening in its bottom, the

inlet being of such dimension in one direca.

tion as to prevent the passage therethrou h of molten metal from the mold cavity y gravity, a reservoir with which said inlet connects said mold cavity, and a sprue opening from the exterior of the mold into said reservoir, said sprue opening being large enough in all cross-sectional dimensions toallow molten metal to flow out therethrough from said reservoir by gravity.

8. A mold provided with a mold cavity having an inlet into its lower portion, said inlet being of such dimension in one direction as to prevent the passage therethrough of. molten metal from the mold cavity by gravity, a reservoir with which said inlet connects said mold cavity, and a sprue opening from the exterior of the mold into said reservoir, said sprue opening being large enough in all cross-sectional dimensions to allow molten metal to flow out therethrough from said reservoir by'gravity, and the total cross-sectional area of said sprue opening being materially less than that of the connection between the reservoir and mold cavity. I

In testimony whereof, I have hereunto signed my name to this specification.

' AUGUST KADOW.

cross-section of said opening being materially greater where it joins the mold cavity than atthe exterior surface of the mold, the said inlet opening being so constructed as to prevent a jet of'metal from traveling in a rectilinear path from the exterior of the mold into the mold cavity. a

7. A mold provided with a mold cavity having an inlet into its lower portion, said 

